1. Field of the Invention
The invention is directed to methods and materials useful in treating anatomical defects by employing tissue engineered structural support members and in particular to methods and materials useful in penile reconstruction.
2. Description of the Background
Conditions such as inadequate and ambiguous genitalia, caused by aphallia, rudimentary penis, severe hypospadias, traumatic injury or pseudohermaphroditism, require surgical intervention. Sex assignment in these patients is made after a thorough diagnostic evaluation and careful consultation with the family. The decision is made based on external genital morphology, hormonal sex and the established gender role. In numerous instances, a decision is made to rear the child as a female, regardless of the karyotype, due to surgical difficulties and poor results with phallic construction.
The penis consists of two parallel cylindrical bodies, the corpora cavernosa, and beneath them the corpus spongiosum, through which the urethra passes. The urethra runs along the underside of the penis then rises to open at the expanded, cone-shaped tip, the glans penis, which fits like a cap over the end of the penis. Loose skin encloses the penis and also forms the retractable foreskin or prepuce. The root of the penis is attached to the descending portions of the pubic bone by the crura, the latter being the extremities of the corpora cavernosa.
There are many causes of impotence. Organic impotence is the loss of the ability to obtain or maintain a functional erection due to the interruption of certain physiologic processes. Causes of organic impotence include trauma such as spinal cord injury or pelvic fracture; postoperative complications such as prostatectomy, cystectomy, external sphincterotomy and abdominal perineal resection; vascular disease such as arteriosclerosis or priapism; neurologic disease such as peripheral neuropathy and multiple sclerosis; endocrinologic and metabolic disease such as diabetes, hypogonadism and renal failure; and medication such as estrogen, parasympatholytic, morphine, and heroin. The complex reflexes entailed in the mechanism of erection are also affected by physiological factors.
Phallic construction was initially attempted in the late 30's using autogenous tissue (See e.g., Goodwin, W. E. et al., Phalloplasty. J. Urol., 68: 903, 1952). Rib cartilage had been used as a stiffener in patients with traumatic penile loss. This method involved multiple stage surgery which did not have a cosmetically satisfactory result (Frumpkin, A. P.: Am. Rev. Sov. Med., 2: 14, 1944). Silicone prostheses have become popularized in the 1970s (Bretan, P. N. Jr.: In: Genitourinary Prostheses. Montague, D. K. (ed), Philadelphia, W. B. Saunders Co., 1989; Small, M. P. et al., Urology, 5: 479, 1975). Although silicone penile prostheses are an accepted treatment modality for adults, complications such as erosion and infection remain a problem (Nukui, F. et al., Int. J. Urol., 4: 52, 1997; Kardar, A. et al., Scan. J. Urol. & Nephrol., 29: 355, 1995). Other problems reported with synthetic prostheses include extrusion through the urethra or sink of the dorsal penile shaft; lymphatic edema; irritation of the glans at the corona; slippage of the glans over the prosthesis; infection of the corpora cavernosa; crural perforation; midshaft septal perforation; and penile pain (Small, M. P. et al., Urology, 5: 479, 1975).
Although silicone penile prostheses are an accepted treatment modality for adults requiring penile reconstruction, its use has not been generally applied to the pediatric population, mainly due to the long-term problems associated with these artificial devices. Thus, there is a need for biocompatible and elastic penile implants that could be used in children who require genital reconstruction.